Shaft coupling



FIG. 1 is a front perspective view of a shaft coupling;

FIG. 2 is a front view thereof;

FIG. 3 is a back view thereof;

FIG. 4 is a left side view thereof;

FIG. 5 is a right side view thereof;

FIG. 6 is a top view thereof; and,

FIG. 7 is a bottom view thereof.

The broken lines represent environment and form no part of the claimed design. 

CLAIM We claim the ornamental design for a shaft coupling, as shown and described. 